A typical differential odometer includes a pair of sensors, one mounted near each rear wheel of a vehicle. Each sensor generates a plurality of output pulses as its associated wheel rotates, and this information is used to compute a dead reckoning position for the vehicle.
To make accurate dead reckoning computations, the wheel sensors should be calibrated. This means that each output pulse from a sensor should correspond to a known distance traveled by its associated wheel.
The conventional method for calibrating wheel sensors requires that an operator drive the vehicle over a straight path, carefully indicating to his navigation system when he comes to the start and finish points on the path. The system can count the number of pulses received from each wheel sensor between the start and finish points, and calculate the distance travelled per pulse for each wheel.
This conventional calibration method is prone to operator errors, and it is not always possible for the operator to find a straight path having a known length with easily discernable start and finish points.
Further, if the path is incorrectly measured, or if the operator did not properly align the vehicle on the path before indicating the start of the path, incorrect calibration may result. Thus, a more reproducible and operator-friendly calibration method is needed.